The specific aims of the research project are to identify the effect of a variety of chemical agents and drugs on the corneal endothelium. (1) Hematoporphyrin, a photosensitizing agent, is used in the treatment of a variety of cancers and has potential value for the treatment of retinoblastoma in the eye. The drug will be investigated for possible phototoxic effects on the corneal endothelium. (2) The effect of a variety of selective anion blockers on corneal endothelium. (2) The effect of a variety of selective anion blockers on corneal endothelial bicarbonate fluxes will be determined and will be related to corneal deturgescence. (3) Cadmium sulfide is a selective sensitizer for the photo-destruction of cysteine residues and proteins. Endothelial bicarbonate fluxes and water movement following destruction of cysteine will be evaluated. (4) Phototherapy, which is commonly used in the treatment of neonatal jaundice, will be investigated to determine whether or not babies are at risk for corneal endothelial damage during phototherapy. (5) Alloxan will be used to determine the effect of endogenously generated free radicals on cornea endothelium. Free radicals mau ultimately be related to the aging process and to the reduction of endothelial cell po;ulation that occurs with increasing age or following intraocular inflammation. (6) Effect of manipulation of intracelluloar glutathione level and redox state will be investigated to determine whether or not endothelial susceptibility to exogenous toxins or corneal storage csn be modified. (7) Free radicals, specifically superoxide anion, and hydroxyl radical as well as hydrogen peroxide may be of importance in the mediation of tissue damage induced ;by inflammation. Effects of these agents on endothelium, intraocular pressure and iris microvascular circulation will be evaluated. The project will investigate basic corneal physiology, the long term application of which is a better understanding of the development of corneal edema and compounds and conditions which may cause it. Each segment of the proposed study will focus on a different aspect of corneal endothelial physiology, and indicate possible ways in which the transport processes may be modified by ambient conditions.